Year	Percent
1991	10.878
1992	10.78
1993	10.609
1994	9.525
1995	10.045
1996	9.743
1997	9.439
1998	10.056
1999	9.711
2000	9.455
2001	8.933
2002	8.903
2003	8.254
2004	8.084
2005	8.51
2006	8.169
2007	7.799
2008	7.358
2009	6.986
2010	6.642
2011	6.428
2012	6.437
2013	6.122
2014	5.998
2015	6.046
2016	6.178
2017	6.2
2018	6.072
2019	5.927
2020	5.864
2021	5.795
2022	5.735